The present invention relates to antioxidants for food substances, more particularly to antioxidants obtained by the extraction of tea leaves at temperatures of at least 120.degree. C. as in certain processes for the production of instant tea.
Lipid autoxidation occurring in foods has always been a concern for both food processors and consumers and the most common method used to inhibit lipid oxidation is the application of synthetic antioxidants which block the oxidative reactions. However, owing to toxicological and nutritional considerations, only a very few synthetic antioxidants are permitted in food applications, e.g., butylhydroxytoluene (BHT), butylhydroxyanisole (BHA), propyl gallate (PG) and t-butyl hydroquinone (TBHQ). Even these antioxidants are now being examined by regulatory agencies and consumer activists and these developments have urged the need to exploit new sources of natural antioxidants.
One natural product with excellent antioxidant properties, Rosemary AR, suffers from the disadvantage of having a very intensive characteristic herb flavour which may limit its use in some applications.
It is also reported in the literature that certain tea extracts have antioxidant properties, e.g., extracts of tea leaves, tea grounds, tea sweepings and tea wastes, but in all the tea extracts so far described, the antioxidant activity is generally very low and the application of each extract is limited to a restricted class of food materials. As far as we are aware, no study on the antioxidant properties of instant tea or the intermediate extracts produced during its manufacture has been documented.